Electrophotographic photoreceptor with superlattice structure

Abstract

An electrophotographic photoreceptor constituted by a conductive substrate, and a photoconductive layer, provided on the conductive substrate, for generating photocarriers upon radiation of light is disclosed. The photoconductive layer has a charge-generating layer and a charge-retaining layer. The charge-generating layer comprises a semiconductor containing silicon as a major constituent. The charge-retaining layer comprises a multilayered body constituted by alternately stacking first amorphous semiconductor layers containing silicon as a major constituent and second amorphous semiconductor layers containing silicon as a major constituent and at least one element selected from the group consisting of carbon, oxygen, and nitrogen. A concentration of the element is changed in a direction of thickness of the charge-retaining layer for each second amorphous semiconductor layer.

What is claimed is: 
     
       1. An electrophotographic photoreceptor comprising a conductive substrate, and a photoconductive layer, provided on said conductive substrate, for generating photocarriers upon radiation of light, wherein said photoconductive layer has a charge-generating layer and a charge-retaining layer, said charge-generating layer comprises a semiconductor containing silicon as a major constituent, said charge-retaining layer comprises a multilayered body constituted by alternately stacking first amorphous semiconductor layers containing silicon as a major constituent and second amorphous semiconductor layers containing silicon as a major constituent and at least one element selected from the group consisting of carbon, oxygen, and nitrogen, and a concentration of said element is changed in a direction of thickness of said charge-retaining layer for each second amorphous semiconductor layer. 
     
     
       2. An electrophotographic photoreceptor according to claim 1, wherein each of said first and second amorphous semiconductor layers has a thickness falling within the range of 30 to 500 Å. 
     
     
       3. An electrophotographic photoreceptor according to claim 1, wherein the concentration of said element contained in each of said second amorphous semiconductor layer falls within the range of 0.5 to 30 atomic %. 
     
     
       4. An electrophotographic photoreceptor according to claim 3, wherein the concentration of said element contained in each of said second amorphous semiconductor layer falls within the range of 5 to 30 atomic %. 
     
     
       5. An electrophotographic photoreceptor according to claim 1, wherein said charge-generating layer contains amorphous silicon and/or microcrystalline silicon. 
     
     
       6. An electrophotographic photoreceptor comprising a conductive substrate, and a photoconductive layer, provided on said conductive substrate, for generating photocarriers upon radiation of light, wherein said photoconductive layer has a charge-generating layer and a charge-retaining layer, said charge-generating layer comprises a semiconductor containing silicon as a major constituent, said charge-retaining layer comprises a multilayered body constituted by alternately stacking first amorphous semiconductor layers containing silicon as a major constituent and a second amorphous semiconductor layers containing silicon as a major constituent and at least one element selected from the group consisting of carbon, oxygen, and nitrogen, and a concentration of said element is changed in a direction of thickness of said charge-retaining layer for each second amorphous semiconductor layer, and wherein said charge-generating layer is constituted by stacking microcrystalline silicon layers having different crystallinities. 
     
     
       7. An electrophotographic photoreceptor according to claim 1, wherein said charge-generating layer is constituted by stacking amorphous silicon layers and microcrystalline silicon layers. 
     
     
       8. An electrophotographic photoreceptor according to claim 1, wherein said semiconductor layers contain hydrogen. 
     
     
       9. An electrophotographic photoreceptor according to claim 1, wherein said photoconductive layer contains an element belonging to Group III or V of the Periodic Table. 
     
     
       10. An electrophotographic photoreceptor according to claim 1, wherein a barrier layer is formed between said photoconductive layer and said conductive substrate. 
     
     
       11. An electrophotographic photoreceptor according to claim 1, wherein a surface layer is formed on said photoconductive layer. 
     
     
       12. An electrophotographic photoreceptor comprising a conductive substrate, and a photoconductive layer, provided on said conductive substrate, for generating photocarriers upon radiation of light, wherein said photoconductive layer has a charge-generating layer and a charge-retaining layer, said charge-generating layer comprises a multilayered body constituted by alternately stacking amorphous semiconductor layers containing silicon as a major constituent and microcrystalline silicon layers containing silicon as a major constituent, a crystallinity of said microcrystalline silicon layers is changed in a direction of thickness of said charge-generating layer for each microcrystalline silicon layer, and said charge-retaining layer comprises a first amorphous semiconductor layer containing silicon as a major constituent and a second amorphous silicon layer containing silicon as a major constituent and at least one element selected from the group consisting of carbon, oxygen, and nitrogen. 
     
     
       13. An electrophotographic photoreceptor according to claim 12, wherein each of said microcrystalline and amorphous semiconductor layers has a thickness falling within the range of 30 to 500 Å. 
     
     
       14. An electrophotographic photoreceptor according to claim 12, wherein the concentration of said element contained in each of said second amorphous semiconductor layer falls within the range of 0.5 to 30 atomic %. 
     
     
       15. An electrophotographic photoreceptor according to claim 14, wherein the concentration of said element contained in each of said second amorphous semiconductor layer falls within the range of 5 to 30 atomic %. 
     
     
       16. An electrophotographic photoreceptor according to claim 12, wherein the crystallinity of said microcrystalline semiconductor layers is changed within a range of 60 to 90%. 
     
     
       17. An electrophotographic photoreceptor according to claim 12, wherein said semiconductor layers contain hydrogen. 
     
     
       18. An electrophotographic photoreceptor according to claim 12, wherein said photoconductive layer contains an element belonging to Group III or V of the Periodic Table. 
     
     
       19. An electrophotographic photoreceptor according to claim 12, wherein a barrier layer is formed between said photoconductive layer and said conductive substrate. 
     
     
       20. An electrophotographic photoreceptor according to claim 12, wherein a surface layer is formed on said photoconductive layer. 
     
     
       21. An electrophotographic photoreceptor according to claim 7, wherein the crystallinity of said microcrystalline silicon layer is changed in a direction of thickness of said charge-generating layer for each microcrystalline silicon layer.